According to known solutions, the two clutches are of the oil-bath type and are fully independent from one another, i.e. they are actuated by dedicated and separate devices, each of which comprises a relative actuator, a relative control device driven for instance by fluid supply and electrovalves in the case in which the actuator is of the oil-hydraulic type, and a relative sensor for controlling the stroke of this actuator.
In the known solutions described above, moreover, when the vehicle is stationary with the engine off, the actuators do not exert any action on the relative clutches, as a result of which the engine of the motor vehicle is uncoupled from both gear changes and, therefore, from the wheels.
The known solutions described above are relatively complex, as they include a relatively large number of components needed to actuate and control the two clutches independently.
The number of components of the motor vehicle is also high because it is necessary to provide an additional parking device of automatic type, for instance of the ratchet gear type, which keeps the wheels braked under the control of complex control and command systems when the motor vehicle is on a sloping road with the engine off.